What is Power Quality? Power Quality (PQ) is a generic term applied to a wide variety of electromagnetic phenomena in the electrical power system. Quite often the term PQ is associated with specific problems with equipment or system for example equipment damage, data problem or loss, equipment malfunction or complete system failure. The duration of these phenomena ranges from a few nanoseconds (e.g., transients) to a few milliseconds (e.g., voltage sags) to steady-state disturbances (harmonic distortions and voltage fluctuations). Why is Power Quality becoming a BIG issue amongst industrial customers? It is important to note that PQ has been an intrinsic feature of the electrical power systems since the earliest times. Yet in recent decades PQ has become an increasingly troublesome disturbance, giving rise to inconvenience and even considerable economic loss. Categories of Power Quality Events Voltage Sags, Swells, Transients, Harmonics, Flickers, Notches, Noises & Unbalance are common names given to all PQ events (IEC 61000-2-1). All these PQ events are termed as electromagnetic disturbances (ED) that form the electromagnetic environment (EE) for all electrical equipment/ device (IEC 61000-2-4/12). What is voltage sag (dip)? The reason is due to the fact that some modern electricity utilization equipment, either in its own design or because of control features incorporated in it, has become more sensitive to PQ events. The sensitivity to such voltage deviations varies from one piece of equipment to another, what may be considered poor PQ to one device may be perfectly acceptable PQ to another. Voltage sag (dip) is a short duration voltage variation and is caused by motor starting, heaters in printers and copiers cycling, as well as faults in the power system. Sags often cause lights to dim or flicker and computer equipment to lock up or lose memory. There is therefore a need for an increased awareness of the phenomenon among the suppliers and users of electricity and the manufacturers of equipment using electricity. Technical definitions of Power Quality Power Quality (PQ) is the concept of powering and grounding sensitive equipment in a manner that is suitable to the operation of that equipment (IEEE Std.1100 & IEEE Std.1159). According to IEEE Std. 1000 & IEC 60364-4-44, voltage sensitive equipment requires full protection against all voltage disturbances. What is the impact of Power Quality? PQ affects the reliable operation of computers and computer-based equipment, which are now so ubiquitous. Often more important than the physical effect on the equipment is the loss of productivity resulting from computer equipment failure, mis-calculations and downtime. According to the Electric Power Research Institute (EPRI) from USA, voltage sags are the number one PQ problem for semiconductor industries and other voltage sensitive industries. Electromagnetic Compatibility (EMC) Power Quality (PQ) is also defined as conducted electromagnetic disturbances present in electrical supply network in the frequency range from 0 to 9 kHz. These conducted disturbances make up the electromagnetic environment (EE) for sensitive electrical device (IEC 61000-2-1) EMC highlights the requirement of a device to work satisfactorily in the existing electromagnetic environment (EE). To ensure several electrical devices can function together, they shall not emit electromagnetic disturbances (emission) and on the other hand must be able to withstand a certain level of electromagnetic disturbances (immunity). compatible with the electromagnetic environment (EE) of the electrical power system. For existing equipment, EMC compliance tests must be performed to verify non compliance. Mitigating measures must then be implemented to improve the equipment non compliance against electromagnetic disturbances (ED). TNB efforts in managing PQ/EMC Every year, TNB organizes FREE awareness programs on PQ/EMC for Prime Customers at all states. TNB has also standardized an internal procedure (ENGR 750-31) to response to all complaints regarding PQ/EMC from Prime Customers. How to handle PQ/EMC issues PQ/EMC problem occurs in every electrical power system around the world. International standard bodies e.g. IEEE (US), SEMI (US) and IEC (Europe) are producing documents on PQ/EMC guidelines and standards as reference to the power utilities, equipment manufacturers and equipment users. TNB also provides technical consultancy on PQ/EMC mitigation. The technical consultancy program comprises of three subprograms:• • • Technical assessment Voltage immunity test (voltage sags) Proposal on mitigation measures to improve EMC For further information on PQ/ EMC please contact: According to the EPRI, as much as 80% of PQ/EMC problems relate to inadequate design for electrical wiring or grounding requirement. The best way to avoid PQ/EMC problem is by ensuring all new equipments to be installed are Asset Management Department (AMD) Distribution Division TNB Wisma TNB, Jalan Timur, Petaling Jaya 46200, Selangor, MALAYSIA Tel : 603-7967 9000 Fax : 603-7960 0360 Understanding Power Quality & Electromagnetic Compatibility